Search for \eta -Mesic Nuclei at J-PARC

The merits of searching for \eta -mesic nuclei by use of the (\pi, N) reaction at J-PARC is discussed, by comparison with an old experiment with the same reaction at BNL in 1980’s. The importance of a pilot experiment using deuterium target is also stressed for a better understanding of the background which should exist even after the coincidence of the decay particles of \eta -mesic nuclei.